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- Title
Facies development and sequence stratigraphy of the Ludfordian (Upper Silurian) deposits in the Zbruch River Valley, Podolia, western Ukraine: local facies overprint on the δC record of a global stable carbon isotope excursion.
- Authors
Jarochowska, Emilia; Kozłowski, Wojciech
- Abstract
The Ludfordian (Upper Silurian) succession in Podolia, western Ukraine, represents a Silurian carbonate platform developed in an epicontinental sea on the shelf of the paleocontinent of Baltica. Coeval deposits throughout this basin record a positive stable carbon isotope excursion known as the Lau excursion. The record of this excursion in Podolia exhibits an unusual amplitude from highly positive (+6.9 ‰) to highly negative (−5.0 ‰) δC values. In order to link δC development with facies, five sections in the Zbruch River Valley were examined, providing microfacies characterization and revised definitions of the Isakivtsy, Prygorodok, and Varnytsya Formations. The Isakivtsy Fm. is developed as dolosparite replacing originally bioclastic limestone. The Prygorodok Fm., recording strongly depleted (down to −10.53 ‰) to near zero (0.12 ‰) δC values is developed as laminated, organic-rich dolomicrite with metabentonite and quartz siltstone beds. The Varnytsya Fm. is characterized by peritidal deposition with consistent, slightly negative δC values (−0.57 to −3.20 ‰). It is proposed that dolomitization of the Isakivtsy Fm. is associated with a sequence boundary and erosional surface. The overlying Prygorodok Fm. represents the proximal part of a TST deposited in restricted and laterally extremely variable environments dominated by microbial carbonate production. The transition to the overlying Varnytsya Fm. facies is marked by a maximum flooding surface. The SB and MFS are potentially correlative within the basin and support a global rapid sea-level fall previously proposed for this interval. The interpretation of the Prygorodok Fm. as coastal lake deposits may explain the unusual δC values and constitute one of the few records of this type of environment identified in the early Paleozoic.
- Subjects
ZBRUCH River Valley (Ukraine); FACIES; CARBONATES; STRATIGRAPHIC geology; SILURIAN Period; CARBON isotopes
- Publication
Facies, 2014, Vol 60, Issue 1, p347
- ISSN
0172-9179
- Publication type
Article
- DOI
10.1007/s10347-013-0370-4